Maverick Scientist Casts an Eye on Pluto : Proposes Way to Probe Distant Planet Years Ahead of Schedule at Small Cost
A maverick engineer at NASA headquarters who has worked magic in the past has come up with a way of getting a spacecraft to Pluto much sooner than expected, thus completing the initial reconnaissance of the solar system.
Tiny Pluto is now the sun’s only planet that has not been visited by a spacecraft from Earth, and National Aeronautics and Space Administration officials have been saying for years that it would cost so much to get there they saw no chance for a Pluto mission for several decades.
But Robert Farquhar, manager of the “small missions program” at NASA headquarters, has come up with a way of getting a spacecraft launched for Pluto in about a dozen years, and he says he can do it for under $150 million. That’s pocket change in the space business.
And with Voyager’s spectacular encounter with Neptune whetting their appetite for more, a lot of other experts are lining up in support of Farquhar’s idea.
Double Duty
Farquhar has proposed “piggybacking” the Pluto project on a high-priority mission that would send a probe darting through the sun’s blistering atmosphere soon after the turn of the century. The solar probe would need to approach the sun from an angle that could only be achieved by first flying by Jupiter, and Farquhar argues that since the solar mission has to go to Jupiter anyway, why not stick a Pluto spacecraft on the same rocket?
At Jupiter, the two probes would part company, with one heading for the sun and the other coasting on to Pluto, a chunk of ice that is the coldest planet in the solar system.
“It’s a free ride,” Farquhar said. “That’s the whole idea.”
Planetary physicist Alan Stern of the University of Colorado has even coined a name for the joint mission that sounds like it came right out of Hollywood: “Fire and Ice.”
The proposal is being taken very seriously at NASA headquarters, sources told The Times, partly because scientists want so desperately to complete the exploration of the planetary system and just one dinky little ball of ice remains to be conquered.
“I find it a very interesting possibility,” said Bruce Tsurutani, a plasma physicist at the Jet Propulsion Laboratory. Tsurutani is planning the solar probe mission that Farquhar has invited himself to join.
Consideration Suggested
Tsurutani sees some possible problems with the idea, but he said Voyager’s encounter with Neptune left him wanting more and he thinks Farquhar ought to at least be given strong consideration.
At this stage of the planning process, NASA officials usually are reluctant to talk about potential missions, but that kind of bureaucratic restraint has never inhibited Farquhar. An expert on orbital mechanics--the engineering wizardry that allows spacecraft to travel for billions of miles and arrive right on target--Farquhar has startled his colleagues in the past.
A few years ago Farquhar and Fred Scarf, a brilliant TRW physicist who died last year while visiting Moscow, electronically pirated an aging spacecraft that was already in orbit but had completed its primary mission.
Farquhar contended that he could redirect the spacecraft, using the Earth’s gravity as a slingshot, to encounter a comet before five international probes reached Halley’s Comet in 1986.
NASA bought his idea and took the spacecraft away from one division and gave it to another. Then Farquhar had a heart attack while trying to figure out the immensely complicated orbital maneuvers.
But he finished his planning while still in his hospital bed and the old spacecraft, renamed the International Cometary Explorer, became the first spacecraft to encounter a comet when it zipped past Giacobini-Zinner just ahead of the Halley armada.
Commands Respect
That stunning achievement is one reason why, when Farquhar speaks, people listen.
Farquhar, who was in Pasadena for the Neptune encounter, said he came up with the Pluto proposal while looking at plans for the solar probe. As manager of the small missions program, Farquhar’s job is to come up with missions that could be done for a fraction of the cost of the multibillion-dollar spectaculars that NASA has favored in recent years.
He said he was struck by the fact that the solar craft would have to first fly by Jupiter, which is more than five times farther from the sun than the Earth is. Scientists want the probe to fly right over the sun’s north pole in a course perpendicular to a line between the Earth and the sun. That way they can study the entire encounter as the probe races through the hot, turbulent gases of the solar corona.
The solar mission is a high-priority project because the sun, which is the only star in the universe that makes life possible on Earth, has been relatively neglected in space exploration.
The solar mission is “on the docket” for the future, said JPL’s Tsurutani.
Tricky Mechanics
It will take a Titan rocket and a tricky bit of orbital mechanics for the solar probe to succeed, a fact that set Farquhar’s brain humming. A few calculations and he determined that the rocket could actually carry more than the solar probe weighs.
“We have an excess weight capability,” he said.
Room for Spacecraft
He concluded that a small spacecraft with a limited range of instruments would fit nicely atop that Titan rocket.
The Titan would launch a single spacecraft containing both probes toward the sun, where it would use the sun’s gravitational field as a slingshot to boost its speed and send it back toward the Earth. The Earth’s gravity would give the craft an additional push, giving it enough velocity to fly out to Jupiter.
At Jupiter, the Pluto probe would separate from the main payload. The solar probe would circle back down to the sun, and the Pluto mission would zip on out toward Pluto, which is so far away it would not get there until about 2014.
“It’s imminently feasible,” said Stern, an expert on Pluto. “In fact, it’s a lot less complicated than most of the things we do.”
The secret to success would lie in simplicity. Farquhar said the craft would be limited to a camera, a dust counter, an atmospheric instrument, and communications gear that would also permit radio science experiments.
“You’ll get great pictures back,” he said.
Stern said the craft would also be equipped with “a modern laser disk” to store tremendous amounts of data. That would permit transmitting the data back to Earth much more slowly so that the size of the craft’s antenna could be reduced.
“There is a problem in that the people become so hungry for the data,” Stern said, recalling the photos that flashed every few minutes on Voyager monitors at JPL. It would take “a month or two” to play back all the data collected at Pluto, he added.
“That will be like watching a snail cross the street,” Stern said.
Package From Earth
As it darted past Pluto, the craft could even send down a package of instruments, he added. That amounts to little more than a sophisticated dart tossed at Pluto, but Stern said such an achievement “would be dynamite.”
There would be a greater risk of failure than most NASA missions because the small probe would not have the redundancies of a craft like Voyager, but at least it offers one way of getting to Pluto in less than a few centuries, Farquhar said.
Even if NASA decides to give the Pluto mission a top priority, it will still take time.
“Fire and Ice” could not be launched until around the turn of the century because it will take several years to put the mission together. And Pluto is more than 32 times farther from the sun than the Earth, a long haul by anyone’s standards.
“My little daughter will be grown by the time it’s launched,” said Stern. “She will have children of her own by the time it gets there.”
FIRE AND ICE (1) A Titan rocket carrying both the solar and Pluto probes would be launched toward the sun, but because that trajectory would not allow the solar probe to pass close by the sun at the right angle, the spacecraft would orbit the sun to pick up speed from the sun’s gravity, and then head back toward Earth.
(2) After passing the Earth, and picking up additional speed from the Earth’s gravity, the craft would have enough speed to fly all the way to Jupiter, where the two probes would separate.
(3) The Pluto probe would go on to the distant planet, which is 32 times farther from the sun than the Earth. The solar probe would continue back to the sun, approaching it at just the right angle to fly over its north pole and through the sun’s hot outer atmosphere, called the corona.
